The KeyboardFocusManager is responsible for managing the active and focused
Windows, and the current focus owner. The focus owner is defined as the
Component in an application that will typically receive all KeyEvents
generated by the user. The focused Window is the Window that is, or
contains, the focus owner. Only a Frame or a Dialog can be the active
Window. The native windowing system may denote the active Window or its
children with special decorations, such as a highlighted title bar. The
active Window is always either the focused Window, or the first Frame or
Dialog that is an owner of the focused Window.

The KeyboardFocusManager is both a centralized location for client code to
query for the focus owner and initiate focus changes, and an event
dispatcher for all FocusEvents, WindowEvents related to focus, and
KeyEvents.

Some browsers partition applets in different code bases into separate
contexts, and establish walls between these contexts. In such a scenario,
there will be one KeyboardFocusManager per context. Other browsers place all
applets into the same context, implying that there will be only a single,
global KeyboardFocusManager for all applets. This behavior is
implementation-dependent. Consult your browser's documentation for more
information. No matter how many contexts there may be, however, there can
never be more than one focus owner, focused Window, or active Window, per
ClassLoader.

dequeueKeyEvents(long after,
Component untilFocused)
Called by the AWT to notify the KeyboardFocusManager that it should
cancel delayed dispatching of KeyEvents.

protected abstract void

discardKeyEvents(Component comp)
Called by the AWT to notify the KeyboardFocusManager that it should
cancel delayed dispatching of KeyEvents.

abstract boolean

dispatchEvent(AWTEvent e)
This method is called by the AWT event dispatcher requesting that the
current KeyboardFocusManager dispatch the specified event on its behalf.

abstract boolean

dispatchKeyEvent(KeyEvent e)
Typically this method will be called by dispatchEvent if no
other KeyEventDispatcher in the dispatcher chain dispatched the
KeyEvent, or if no other KeyEventDispatchers are registered.

void

downFocusCycle()
Moves the focus down one focus traversal cycle from the current focus
owner, if and only if the current focus owner is a Container that is a
focus cycle root.

enqueueKeyEvents(long after,
Component untilFocused)
Called by the AWT to notify the KeyboardFocusManager that it should
delay dispatching of KeyEvents until the specified Component becomes
the focus owner.

processKeyEvent(Component focusedComponent,
KeyEvent e)
This method initiates a focus traversal operation if and only if the
KeyEvent represents a focus traversal key for the specified
focusedComponent.

void

redispatchEvent(Component target,
AWTEvent e)
Redispatches an AWTEvent in such a way that the AWT event dispatcher
will not recursively request that the KeyboardFocusManager, or any
installed KeyEventDispatchers, dispatch the event again.

setCurrentKeyboardFocusManager

Sets the current KeyboardFocusManager instance for the calling thread's
context. If null is specified, then the current KeyboardFocusManager
is replaced with a new instance of DefaultKeyboardFocusManager.

If a SecurityManager is installed, the calling thread must be granted
the AWTPermission "replaceKeyboardFocusManager" in order to replace the
the current KeyboardFocusManager. If this permission is not granted,
this method will throw a SecurityException, and the current
KeyboardFocusManager will be unchanged.

Parameters:

newManager - the new KeyboardFocusManager for this thread's context

Throws:

SecurityException - if the calling thread does not have permission
to replace the current KeyboardFocusManager

getFocusOwner

Returns the focus owner, if the focus owner is in the same context as
the calling thread. The focus owner is defined as the Component in an
application that will typically receive all KeyEvents generated by the
user. KeyEvents which map to the focus owner's focus traversal keys will
not be delivered if focus traversal keys are enabled for the focus
owner. In addition, KeyEventDispatchers may retarget or consume
KeyEvents before they reach the focus owner.

Returns:

the focus owner, or null if the focus owner is not a member of
the calling thread's context

getGlobalFocusOwner

Returns the focus owner, even if the calling thread is in a different
context than the focus owner. The focus owner is defined as the
Component in an application that will typically receive all KeyEvents
generated by the user. KeyEvents which map to the focus owner's focus
traversal keys will not be delivered if focus traversal keys are enabled
for the focus owner. In addition, KeyEventDispatchers may retarget or
consume KeyEvents before they reach the focus owner.

This method will throw a SecurityException if this KeyboardFocusManager
is not the current KeyboardFocusManager for the calling thread's
context.

Returns:

the focus owner

Throws:

SecurityException - if this KeyboardFocusManager is not the
current KeyboardFocusManager for the calling thread's context

setGlobalFocusOwner

Sets the focus owner. The operation will be cancelled if the Component
is not focusable. The focus owner is defined as the Component in an
application that will typically receive all KeyEvents generated by the
user. KeyEvents which map to the focus owner's focus traversal keys will
not be delivered if focus traversal keys are enabled for the focus
owner. In addition, KeyEventDispatchers may retarget or consume
KeyEvents before they reach the focus owner.

This method does not actually set the focus to the specified Component.
It merely stores the value to be subsequently returned by
getFocusOwner(). Use Component.requestFocus()
or Component.requestFocusInWindow() to change the focus
owner, subject to platform limitations.

clearGlobalFocusOwner

public void clearGlobalFocusOwner()

Clears the global focus owner at both the Java and native levels. If
there exists a focus owner, that Component will receive a permanent
FOCUS_LOST event. After this operation completes, the native windowing
system will discard all user-generated KeyEvents until the user selects
a new Component to receive focus, or a Component is given focus
explicitly via a call to requestFocus(). This operation
does not change the focused or active Windows.

getPermanentFocusOwner

Returns the permanent focus owner, if the permanent focus owner is in
the same context as the calling thread. The permanent focus owner is
defined as the last Component in an application to receive a permanent
FOCUS_GAINED event. The focus owner and permanent focus owner are
equivalent unless a temporary focus change is currently in effect. In
such a situation, the permanent focus owner will again be the focus
owner when the temporary focus change ends.

Returns:

the permanent focus owner, or null if the permanent focus owner
is not a member of the calling thread's context

getGlobalPermanentFocusOwner

Returns the permanent focus owner, even if the calling thread is in a
different context than the permanent focus owner. The permanent focus
owner is defined as the last Component in an application to receive a
permanent FOCUS_GAINED event. The focus owner and permanent focus owner
are equivalent unless a temporary focus change is currently in effect.
In such a situation, the permanent focus owner will again be the focus
owner when the temporary focus change ends.

This method will throw a SecurityException if this KeyboardFocusManager
is not the current KeyboardFocusManager for the calling thread's
context.

Returns:

the permanent focus owner

Throws:

SecurityException - if this KeyboardFocusManager is not the
current KeyboardFocusManager for the calling thread's context

setGlobalPermanentFocusOwner

Sets the permanent focus owner. The operation will be cancelled if the
Component is not focusable. The permanent focus owner is defined as the
last Component in an application to receive a permanent FOCUS_GAINED
event. The focus owner and permanent focus owner are equivalent unless
a temporary focus change is currently in effect. In such a situation,
the permanent focus owner will again be the focus owner when the
temporary focus change ends.

This method does not actually set the focus to the specified Component.
It merely stores the value to be subsequently returned by
getPermanentFocusOwner(). Use
Component.requestFocus() or
Component.requestFocusInWindow() to change the focus owner,
subject to platform limitations.

setGlobalFocusedWindow

Sets the focused Window. The focused Window is the Window that is or
contains the focus owner. The operation will be cancelled if the
specified Window to focus is not a focusable Window.

This method does not actually change the focused Window as far as the
native windowing system is concerned. It merely stores the value to be
subsequently returned by getFocusedWindow(). Use
Component.requestFocus() or
Component.requestFocusInWindow() to change the focused
Window, subject to platform limitations.

getActiveWindow

Returns the active Window, if the active Window is in the same context
as the calling thread. Only a Frame or a Dialog can be the active
Window. The native windowing system may denote the active Window or its
children with special decorations, such as a highlighted title bar.
The active Window is always either the focused Window, or the first
Frame or Dialog that is an owner of the focused Window.

Returns:

the active Window, or null if the active Window is not a member
of the calling thread's context

getGlobalActiveWindow

Returns the active Window, even if the calling thread is in a different
context than the active Window. Only a Frame or a Dialog can be the
active Window. The native windowing system may denote the active Window
or its children with special decorations, such as a highlighted title
bar. The active Window is always either the focused Window, or the first
Frame or Dialog that is an owner of the focused Window.

This method will throw a SecurityException if this KeyboardFocusManager
is not the current KeyboardFocusManager for the calling thread's
context.

Returns:

the active Window

Throws:

SecurityException - if this KeyboardFocusManager is not the
current KeyboardFocusManager for the calling thread's context

setGlobalActiveWindow

Sets the active Window. Only a Frame or a Dialog can be the active
Window. The native windowing system may denote the active Window or its
children with special decorations, such as a highlighted title bar. The
active Window is always either the focused Window, or the first Frame or
Dialog that is an owner of the focused Window.

This method does not actually change the active Window as far as the
native windowing system is concerned. It merely stores the value to be
subsequently returned by getActiveWindow(). Use
Component.requestFocus() or
Component.requestFocusInWindow()to change the active
Window, subject to platform limitations.

setDefaultFocusTraversalPolicy

Sets the default FocusTraversalPolicy. Top-level components
use this value on their creation to initialize their own focus traversal
policy by explicit call to Container.setFocusTraversalPolicy.
Note: this call doesn't affect already created components as they have
their policy initialized. Only new components will use this policy as
their default policy.

setDefaultFocusTraversalKeys

Sets the default focus traversal keys for a given traversal operation.
This traversal key Set will be in effect on all
Windows that have no such Set of
their own explicitly defined. This Set will also be
inherited, recursively, by any child Component of
those Windows that has
no such Set of its own explicitly defined.

The default values for the default focus traversal keys are
implementation-dependent. Sun recommends that all implementations for a
particular native platform use the same default values. The
recommendations for Windows and Unix are listed below. These
recommendations are used in the Sun AWT implementations.

Identifier

Meaning

Default

KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS

Normal forward keyboard traversal

TAB on KEY_PRESSED,
CTRL-TAB on KEY_PRESSED

KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS

Normal reverse keyboard traversal

SHIFT-TAB on KEY_PRESSED,
CTRL-SHIFT-TAB on KEY_PRESSED

KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS

Go up one focus traversal cycle

none

KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS

Go down one focus traversal cycle

none

To disable a traversal key, use an empty Set;
Collections.EMPTY_SET is recommended.

Using the AWTKeyStroke API, client code can
specify on which of two
specific KeyEvents, KEY_PRESSED or
KEY_RELEASED, the focus traversal operation will
occur. Regardless of which KeyEvent is specified,
however, all KeyEvents related to the focus
traversal key, including the associated KEY_TYPED
event, will be consumed, and will not be dispatched
to any Component. It is a runtime error to
specify a KEY_TYPED event as
mapping to a focus traversal operation, or to map the same event to
multiple default focus traversal operations.

Parameters:

id - one of
KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or
KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS

keystrokes - the Set of AWTKeyStrokes for the
specified operation

Throws:

IllegalArgumentException - if id is not one of
KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or
KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS,
or if keystrokes is null,
or if keystrokes contains null,
or if any Object in
keystrokes is not an AWTKeyStroke,
or if any keystroke
represents a KEY_TYPED event,
or if any keystroke already maps
to another default focus traversal operation

getDefaultFocusTraversalKeys

Returns a Set of default focus traversal keys for a given traversal
operation. This traversal key Set will be in effect on all Windows that
have no such Set of their own explicitly defined. This Set will also be
inherited, recursively, by any child Component of those Windows that has
no such Set of its own explicitly defined. (See
setDefaultFocusTraversalKeys for a full description of each
operation.)

Parameters:

id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or
KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS

Returns:

the Set of AWTKeyStrokes
for the specified operation; the Set
will be unmodifiable, and may be empty; null
will never be returned

Throws:

IllegalArgumentException - if id is not one of
KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or
KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS

getCurrentFocusCycleRoot

Returns the current focus cycle root, if the current focus cycle root is
in the same context as the calling thread. If the focus owner is itself
a focus cycle root, then it may be ambiguous as to which Components
represent the next and previous Components to focus during normal focus
traversal. In that case, the current focus cycle root is used to
differentiate among the possibilities.

This method is intended to be used only by KeyboardFocusManagers and
focus implementations. It is not for general client use.

Returns:

the current focus cycle root, or null if the current focus cycle
root is not a member of the calling thread's context

getGlobalCurrentFocusCycleRoot

Returns the current focus cycle root, even if the calling thread is in a
different context than the current focus cycle root. If the focus owner
is itself a focus cycle root, then it may be ambiguous as to which
Components represent the next and previous Components to focus during
normal focus traversal. In that case, the current focus cycle root is
used to differentiate among the possibilities.

This method will throw a SecurityException if this KeyboardFocusManager
is not the current KeyboardFocusManager for the calling thread's
context.

Returns:

the current focus cycle root, or null if the current focus cycle
root is not a member of the calling thread's context

Throws:

SecurityException - if this KeyboardFocusManager is not the
current KeyboardFocusManager for the calling thread's context

setGlobalCurrentFocusCycleRoot

Sets the current focus cycle root. If the focus owner is itself a focus
cycle root, then it may be ambiguous as to which Components represent
the next and previous Components to focus during normal focus traversal.
In that case, the current focus cycle root is used to differentiate
among the possibilities.

This method is intended to be used only by KeyboardFocusManagers and
focus implementations. It is not for general client use.

firePropertyChange

Fires a PropertyChangeEvent in response to a change in a bound property.
The event will be delivered to all registered PropertyChangeListeners.
No event will be delivered if oldValue and newValue are the same.

fireVetoableChange

Fires a PropertyChangeEvent in response to a change in a vetoable
property. The event will be delivered to all registered
VetoableChangeListeners. If a VetoableChangeListener throws a
PropertyVetoException, a new event is fired reverting all
VetoableChangeListeners to the old value and the exception is then
rethrown. No event will be delivered if oldValue and newValue are the
same.

addKeyEventDispatcher

Adds a KeyEventDispatcher to this KeyboardFocusManager's dispatcher
chain. This KeyboardFocusManager will request that each
KeyEventDispatcher dispatch KeyEvents generated by the user before
finally dispatching the KeyEvent itself. KeyEventDispatchers will be
notified in the order in which they were added. Notifications will halt
as soon as one KeyEventDispatcher returns true from its
dispatchKeyEvent method. There is no limit to the total
number of KeyEventDispatchers which can be added, nor to the number of
times which a particular KeyEventDispatcher instance can be added.

If a null dispatcher is specified, no action is taken and no exception
is thrown.

removeKeyEventDispatcher

Removes a KeyEventDispatcher which was previously added to this
KeyboardFocusManager's dispatcher chain. This KeyboardFocusManager
cannot itself be removed, unless it was explicitly re-registered via a
call to addKeyEventDispatcher.

If a null dispatcher is specified, if the specified dispatcher is not
in the dispatcher chain, or if this KeyboardFocusManager is specified
without having been explicitly re-registered, no action is taken and no
exception is thrown.

Parameters:

dispatcher - the KeyEventDispatcher to remove from the dispatcher
chain

getKeyEventDispatchers

Returns this KeyboardFocusManager's KeyEventDispatcher chain as a List.
The List will not include this KeyboardFocusManager unless it was
explicitly re-registered via a call to
addKeyEventDispatcher. If no other KeyEventDispatchers are
registered, implementations are free to return null or a List of length
0. Client code should not assume one behavior over another, nor should
it assume that the behavior, once established, will not change.

addKeyEventPostProcessor

Adds a KeyEventPostProcessor to this KeyboardFocusManager's post-
processor chain. After a KeyEvent has been dispatched to and handled by
its target, KeyboardFocusManager will request that each
KeyEventPostProcessor perform any necessary post-processing as part
of the KeyEvent's final resolution. KeyEventPostProcessors
will be notified in the order in which they were added; the current
KeyboardFocusManager will be notified last. Notifications will halt
as soon as one KeyEventPostProcessor returns true from its
postProcessKeyEvent method. There is no limit to the the
total number of KeyEventPostProcessors that can be added, nor to the
number of times that a particular KeyEventPostProcessor instance can be
added.

If a null post-processor is specified, no action is taken and no
exception is thrown.

Parameters:

processor - the KeyEventPostProcessor to add to the post-processor
chain

removeKeyEventPostProcessor

Removes a previously added KeyEventPostProcessor from this
KeyboardFocusManager's post-processor chain. This KeyboardFocusManager
cannot itself be entirely removed from the chain. Only additional
references added via addKeyEventPostProcessor can be
removed.

If a null post-processor is specified, if the specified post-processor
is not in the post-processor chain, or if this KeyboardFocusManager is
specified without having been explicitly added, no action is taken and
no exception is thrown.

Parameters:

processor - the KeyEventPostProcessor to remove from the post-
processor chain

getKeyEventPostProcessors

Returns this KeyboardFocusManager's KeyEventPostProcessor chain as a
List. The List will not include this KeyboardFocusManager unless it was
explicitly added via a call to addKeyEventPostProcessor. If
no KeyEventPostProcessors are registered, implementations are free to
return null or a List of length 0. Client code should not assume one
behavior over another, nor should it assume that the behavior, once
established, will not change.

dispatchEvent

This method is called by the AWT event dispatcher requesting that the
current KeyboardFocusManager dispatch the specified event on its behalf.
It is expected that all KeyboardFocusManagers will dispatch all
FocusEvents, all WindowEvents related to focus, and all KeyEvents.
These events should be dispatched based on the KeyboardFocusManager's
notion of the focus owner and the focused and active Windows, sometimes
overriding the source of the specified AWTEvent. Dispatching must be
done using redispatchEvent to prevent the AWT event
dispatcher from recursively requesting that the KeyboardFocusManager
dispatch the event again. If this method returns false,
then the AWT event dispatcher will attempt to dispatch the event itself.

redispatchEvent

Redispatches an AWTEvent in such a way that the AWT event dispatcher
will not recursively request that the KeyboardFocusManager, or any
installed KeyEventDispatchers, dispatch the event again. Client
implementations of dispatchEvent and client-defined
KeyEventDispatchers must call redispatchEvent(target, e)
instead of target.dispatchEvent(e) to dispatch an event.

This method is intended to be used only by KeyboardFocusManagers and
KeyEventDispatchers. It is not for general client use.

dispatchKeyEvent

Typically this method will be called by dispatchEvent if no
other KeyEventDispatcher in the dispatcher chain dispatched the
KeyEvent, or if no other KeyEventDispatchers are registered. If an
implementation of this method returns false,
dispatchEvent may try to dispatch the KeyEvent itself, or
may simply return false. If true is returned,
dispatchEvent should return true as well.

processKeyEvent

This method initiates a focus traversal operation if and only if the
KeyEvent represents a focus traversal key for the specified
focusedComponent. It is expected that focusedComponent is the current
focus owner, although this need not be the case. If it is not,
focus traversal will nevertheless proceed as if focusedComponent
were the current focus owner.

Parameters:

focusedComponent - the Component that will be the basis for a focus
traversal operation if the specified event represents a focus
traversal key for the Component

e - the event that may represent a focus traversal key

enqueueKeyEvents

Called by the AWT to notify the KeyboardFocusManager that it should
delay dispatching of KeyEvents until the specified Component becomes
the focus owner. If client code requests a focus change, and the AWT
determines that this request might be granted by the native windowing
system, then the AWT will call this method. It is the responsibility of
the KeyboardFocusManager to delay dispatching of KeyEvents with
timestamps later than the specified time stamp until the specified
Component receives a FOCUS_GAINED event, or the AWT cancels the delay
request by invoking dequeueKeyEvents or
discardKeyEvents.

Parameters:

after - timestamp of current event, or the current, system time if
the current event has no timestamp, or the AWT cannot determine
which event is currently being handled

untilFocused - Component which should receive a FOCUS_GAINED event
before any pending KeyEvents

dequeueKeyEvents

Called by the AWT to notify the KeyboardFocusManager that it should
cancel delayed dispatching of KeyEvents. All KeyEvents which were
enqueued because of a call to enqueueKeyEvents with the
same timestamp and Component should be released for normal dispatching
to the current focus owner. If the given timestamp is less than zero,
the outstanding enqueue request for the given Component with the
oldest timestamp (if any) should be cancelled.

Parameters:

after - the timestamp specified in the call to
enqueueKeyEvents, or any value < 0

untilFocused - the Component specified in the call to
enqueueKeyEvents

discardKeyEvents

Called by the AWT to notify the KeyboardFocusManager that it should
cancel delayed dispatching of KeyEvents. All KeyEvents which were
enqueued because of one or more calls to enqueueKeyEvents
with the same Component should be discarded.

Parameters:

comp - the Component specified in one or more calls to
enqueueKeyEvents

upFocusCycle

Moves the focus up one focus traversal cycle. Typically, the focus owner
is set to aComponent's focus cycle root, and the current focus cycle
root is set to the new focus owner's focus cycle root. If, however,
aComponent's focus cycle root is a Window, then typically the focus
owner is set to the Window's default Component to focus, and the current
focus cycle root is unchanged.

Parameters:

aComponent - the Component that is the basis for the focus
traversal operation

downFocusCycle

Moves the focus down one focus traversal cycle. Typically, if
aContainer is a focus cycle root, then the focus owner is set to
aContainer's default Component to focus, and the current focus cycle
root is set to aContainer. If aContainer is not a focus cycle root, then
no focus traversal operation occurs.

Parameters:

aContainer - the Container that is the basis for the focus
traversal operation

focusNextComponent

public final void focusNextComponent()

Focuses the Component after the current focus owner.

focusPreviousComponent

public final void focusPreviousComponent()

Focuses the Component before the current focus owner.

upFocusCycle

public final void upFocusCycle()

Moves the focus up one focus traversal cycle from the current focus
owner. Typically, the new focus owner is set to the current focus
owner's focus cycle root, and the current focus cycle root is set to the
new focus owner's focus cycle root. If, however, the current focus
owner's focus cycle root is a Window, then typically the focus owner is
set to the focus cycle root's default Component to focus, and the
current focus cycle root is unchanged.

downFocusCycle

public final void downFocusCycle()

Moves the focus down one focus traversal cycle from the current focus
owner, if and only if the current focus owner is a Container that is a
focus cycle root. Typically, the focus owner is set to the current focus
owner's default Component to focus, and the current focus cycle root is
set to the current focus owner. If the current focus owner is not a
Container that is a focus cycle root, then no focus traversal operation
occurs.